Automation

QuickStart Module

This quickstart module is an overview of automation using workflows and processes.

Automation Introduction

The final part of this developer track shows how to create a workflow to simplify tasks and use processes to trigger those workflows.

Workflow

A workflow is a flow-diagram that consists of a start node, 1 or more actions leading to 1 or more exit points.

There are a few pieces of terminology used with workflows, so the following table helps decipher them:

Term	BPMN Term	Description
Action	Activity	A unit of work within a workflow that runs some code to perform a part of the workflow
Event	Event	A state within the workflow, they can be start, end or intermediate
Gateway	Gateway	A special type of action used for making a decision about routing
Phase	Swim Lane	A virtual section of a workflow that can be individually monitored, retried and re-scheduled
Start	Start Event	The virtual start node of a workflow
Step	Step	Either an action, gateway or event
Transition	Connector	A connector between steps of a workflow
Workflow	Workflow	The entire flow encapsulating the phases, transitions and actions

Creating a workflow

To create a workflow in OpenDataDSL we create a workflow structure, the simplest workflow is shown below:

wf_hello = workflow in "test"
    WF_START
        "ok" -> stopok
    end
    WF_EVENT stopok as "success"
        return "ok"
    end
end

This workflow simply has a start node and an end node, but doesn't perform any actions.

Creating an action

Let's create an action called hello_message to create a greeting to the user where the input will be the property user, who we will say hello to. The output will be the property message which will be the greeting string. We configure a single transition out of our action called ok which we return from the action.

The first 3 lines of the action configure the in variable(s), the out variable(s) and the exit transition(s). The rest of the action is the code we want to run and we always return the name of the exit transition that the workflow should follow.

hello_message = action in "general"
    in user as Scalar
    out message as Scalar
    exit "ok"

    output.message = "Hello " + input.user
    return "ok"
end

In-Depth Information

Adding our action to the workflow

In order to add actions to the workflow, we need to introduce a phase. A phase breaks the workflow down into manageable sections.

We then need to reference our action within a WF_ACTION structure, in here we configure the action by mapping input data to it and routing the exit transitions from the action within our workflow.

In the code below we add the phase and configure our action in the simple workflow.

wf_hello = workflow in "test"
    in user as Scalar

    WF_START
        "ok" -> act_print
    end

    phase "MAIN"
        WF_ACTION act_print ai
            "ok" -> stopok
            ai.user = input.user
            result = hello_message.run(ai, output)
        end
    end
    
    WF_EVENT stopok as "success"
        return "ok"
    end
end

To run this workflow, run the following code:

objin = Object()
objin.user = "ODSL"
objout = Object()
wf_hello.run(objin, objout)
print objout.wf_hello.act_print.message

After running the action you should see the message Hello ODSL printed in the debug console.

Preparing for automation

The example we have run works ok for running in a script locally, but in order to modularise it for automating via a process we need to make a change to the way the workflow uses the action.

Saving the action

We need to save the action to the server and get the workflow to load the action when we run it, that way we can make changes to our action without changing the workflow.

To save the action:

save ${action:hello_message}

Change the workflow and save it

The change we need to make to the workflow in order to use our saved action is as follows:

    phase "MAIN"
        WF_ACTION act_print ai
            "ok" -> stopok
            ai.user = input.user
            result = ${action:"hello_message"}.run(ai, output)
        end
    end

With this change in place, we now need to save our workflow using the following:

save ${workflow:wf_hello}

Process

The key to automating a workflow is to create a process that configures and schedules the running of the workflow.

Creating a process

Here is the process to run our workflow with the input user value set on the process and scheduled to run every weekday at 17:00

process = Process()
process.service = "TEST"
process.name = "HELLO_ODSL"
process.workflow = "wf_hello"
process.input.user = "ODSL"
process.cron = "0 17 ? * MON,TUE,WED,THU,FRI *"

save ${process:process}

We can create multiple processes using the same workflow but with different configurations, e.g.

process = Process()
process.service = "TEST"
process.name = "HELLO_WORLD"
process.workflow = "wf_hello"
process.input.user = "World"
process.cron = "0 16 ? * MON,TUE,WED,THU,FRI *"

save ${process:process}

More Information